1. Using Dirt to Solve Crimes
Forensic Geology
Using Dirt to Solve Crimes

2. Forensic Soil Analysis
Search for the:
the link between earthen materials that have been transferred to other objects or locations.
possible origin or sources of the earthen material.

3. History of Forensic Geology
1887–1893 Sir Arthur Conan Doyle
Sherlock Holmes used composition of soil and mud samples to help link an individual to a specific location where a crime had been committed.
This was not a practice used by police of that time.

4. History of Forensic Geology
1893 Hans Gross, a Austrian criminal investigator
wrote in his book Criminal Investigation
there should be a study of “dust, dirt on shoes and spots on cloth.”
“Dirt on shoes can often tell us more about where the wearer of those shoes had last been than toilsome inquiries.”

5. History of Forensic Geology
Murder case in 1904 was the first use of soil evidence to solve a crime.
A seamstress named Eva Disch was strangled by Karl Laubach.
Georg Popp, a German forensic scientist linked soil evidence from Laubach’s pants to a handkerchief left at the crime scene.

6. Soil Evidence and Other Historical Cases
WWII – Japanese balloon bombs
American geologist determined that the sand in the counterweights came from a particular beach in Japan.
Cattle rustlers took cattle from Missouri to Montana.
Analysis of the cow manure revealed fragments of rock made of silica which was a rock only found in Missouri.

8. Formation of Soil
Upper layer of earth that is capable of supporting plant growth
Soil is formed from the weathering of rocks and minerals
Also contains:
Minerals
Decaying organisms
Water
Air

10. Soil Formation Influence By
Parent material
type of rock minerals present
Climate
Temperature
Rainfall
Wind
Topography
Slope of Landscape
Biological Factors
Plants
Animals,
Micro-organisms
Human interaction
Time
“old” soil vs. “new” soil
Soil composition over time

11. Soil Properties Physical Properties Chemical Properties Density
Magnetism
Particle size
Mineral content
Color
Conductivity
Heat Capacity
Chemical Properties pH
elements present
Nitrogen
Phosphorous
Potassium
Calcium

13. Identification of Soil
Soil is identified based on particle size as one of three classifications:
Sand to 2.00 mm
Silt – to 0.05 mm
Clay – less than mm

14. Soil Classifications
Classified by texture which is the result of how much of each type of soil (sand, silt, and clay) is present .
Classifications are typically named for the most abundant particle size or a combination of the most abundant particles sizes
Ex: "sandy clay" or "silty clay."

15. Soil Classifications
A fourth term, loam, is used to describe a combination of sand, silt, and clay.

17. Soil as Evidence Soil is considered Class Evidence
Evidential value of soil can be excellent because:
Types of earth material are virtually unlimited.
Have a wide distribution and change over short distances.
The statistical probability of a given sample having properties the same as another is very small

18. Soil as Evidence Value increases if it contains:
Rare or unusual minerals
Rocks
Fossils
Manufactured particles
More than 2,000 minerals have been identified.
Twenty or so are commonly found in soils; most soil samples contain only three to five.

20. Forensic Soil Examination
Forensic Scientist will analyze the physical and chemical characteristics of the soil such as :
Size
Shape
Color
Mineral content
Organic material content pH

21. Forensic Soil Examination
X-ray diffraction is a specific technique used to determine the mineral composition of the soil
Soil sample is crushed into a fine powder which is then tested
X-ray is deflected off the powder and produces a pattern on film
Each mineral and chemical produces a specific pattern
Electron microscope can be used to identify particles